Patent Documents 1 and 2 disclose a technology for abutting metal members on each other to be formed into a T shape as viewed from a front side, and for performing friction stir joining on the abutment portion. In the conventional technology, an end face of a first metal member is inserted into a recess formed on a rear face of a second metal member, and subsequently a rotary tool is inserted from a front face side of the second metal member, to perform friction stir joining on the abutment portion.
As performance of electronic apparatuses such as a personal computer has advanced recently, an amount of heat generated in a CPU (heat generating body) that is mounted on the electronic apparatuses has been increasing, thereby, cooling down the CPU has been important. A heat sink in an air cooling fan type has been conventionally used to cool down the CPU, however, problems such as noises by fans and cooling limits in the air cooling system is highlighted, thus, a liquid cooling jacket is attracting attention as a next-generation cooling system.
Patent Document 3 discloses a liquid cooling jacket constituted by a jacket body provided with a support part in the center thereof and a sealing body. In a method of manufacturing the liquid cooling jacket, the sealing body is disposed on the jacket body to form an overlapped portion, and subsequently friction stir joining is performed on the overlapped portion.